Ultrasonic surgical instruments, such as ultrasonic scalpels, are finding increasingly widespread application in surgical procedures by virtue of their unique performance characteristics. Depending upon specific device configurations and operational parameters, ultrasonic surgical instruments can provide substantially simultaneous transection of tissue and haemostasis by coagulation, desirably minimizing patient trauma. An ultrasonic surgical instrument can include an ultrasonic transducer and a distally-mounted end effector (e.g., a blade tip) coupled to the transducer and configured to cut and seal tissue. The end effector transmits ultrasonic energy to tissue brought into contact with the end effector to realize cutting and sealing action. Ultrasonic energy can be transmitted to the end effector by a generator system in communication with the instrument.
Electrosurgical instruments for applying electrical energy to tissue (e.g., in order to treat and/or destroy the tissue) are also finding increasingly widespread application in surgical procedures. An electrosurgical instrument can include a distally-mounted end effector (e.g., having one or more electrodes). The end effector can be positioned against the tissue such that electrical current is introduced into the tissue. Electrosurgical instruments can be configured for bipolar or monopolar operation. During bipolar operation, current is introduced into and returned from the tissue by active and return electrodes, respectively, of the end effector. During monopolar operation, current is introduced into the tissue by an active electrode of the end effector and returned through a return electrode (e.g., a grounding pad) separately located on a patient's body. Heat generated by the current flow through the tissue can form haemostatic seals within the tissue and/or between tissues and thus can be particularly useful for sealing blood vessels, for example. The end effector of an electrosurgical instrument can also include a cutting member that is movable relative to the tissue and the electrodes to transect the tissue. Electrical energy can be transmitted to the end effector by a generator system in communication with the instrument. The electrical energy can be in the form of radio frequency (“RF”) energy (e.g., in the frequency range of about 100 kHz to about 1 MHz). In operation, an electrosurgical instrument can transmit RF energy through tissue, which can cause ionic agitation, friction, and/or resistive heating, thereby increasing the temperature of the tissue.
Exemplary surgical generator systems for driving ultrasonic surgical devices and/or electrosurgical devices are disclosed in U.S. Pat. No. 8,986,302 issued on Mar. 24, 2015 and entitled “SURGICAL GENERATOR FOR ULTRASONIC AND ELECTROSURGICAL DEVICES,” which is hereby incorporated herein by reference in its entirety. While these generator systems possess an impressive array of capabilities, there is a continuing need for improved generator systems.